Cryptographic Governance Stack for Human-AI Decision Systems: Authentication Binding, Tenant-Isolated Key Management, and Public Receipt Verification

This record documents the cryptographic governance layer of APR-Lite, a governance engine for protecting human decision authority from AI-influenced outputs in regulated industries. Phases 11–13 deliver a three-layer stack that transforms governance state from an internal audit mechanism into an externally auditable one. The architectural shift: prior to these phases, every governance guarantee required trusting that the substrate was operating correctly. After these phases, governance events produce self-contained proof artifacts that any party can verify independently — without substrate access, without trusting the issuer, without trusting the caller. Tamper invariant: a single field modification in a signed payload produces a failed verification. The substrate does not request trust — it offers proofs. Cumulative verified baseline: 220 tests passing across all suites. Zero failures.